This invention relates to a mechanism for locating an endless photoconductor relative to magnetic brushes of development stations adjacent a path for the photoconductor.
U.S. Pat. No. 3,974,952 entitled Web Tracking Apparatus issued on Aug. 17, 1976 in the names of T. Swanke et al. The apparatus disclosed in that patent includes a pair of spaced, fixed plates for supporting a plurality of rollers. An endless flexible photoconductor is carried by the rollers and advanced past a series of stations, including a single development station that is outside the endless loop formed by the photoconductor. A series of back-up rollers between the plates are located inside the loop formed by the photoconductor and opposite the development station to help establish the plane of the photoconductor relative to the development station.
Apparatus as generally described above has been used successfully in prior copiers/duplicators. In one such copier/dupicator, as the development station is moved into place relative to the photoconductor, the toning roller of a magnetic brush apparatus is located with respect to the back-up roller (and thus the photoconductor) by a four-point mounting including a guide. This system has several disadvantages. For example, the four point system is an over restrained system, it does not always provide the required accuracy of alignment relative to the back-up rollers and photoconductors, and it makes removal of the station difficult. In another copier/duplicator the development station moves into position in a tray and adjustments are provided to move the toning roller with respect to the photoconductor and the back-up roller. These prior systems work satisfactorily even though the back-up roller, toning roller and photoconductor may not be precisely located with respect to each other, especially in a front-to rear direction (i.e., laterally relative to the photoconductor). However, new development stations for an improved developer material require more accuracy in establishment of the plane of the photoconductor with respect to the toning rollers. Thus, improved mechanisms are needed to meet this requirement.
Sometimes a reproduction apparatus is provided with two or more development stations for developing latent images with toner particles of two or more colors. In order to develop each latent image on a photoconductor with toner particles of only one color, the development stations can be moved alternately toward and away from the photoconductor. However, the stations are heavy, and the mechanisms for moving them must be able to operate fast and accurately for satisfactory development of the images. Movement of the stations may be necessary for a rigid drum type photoconductor, but when the photoconductor is flexible, it is clearly more desirable to move the photoconductor relative to the stations.